Electroconductive substrate, electronic device and display device

ABSTRACT

An electroconductive substrate, including: a base material; a foundation layer disposed on the base material; a trench formation layer disposed on the foundation layer, and an electroconductive pattern layer including metal plating. A trench including a bottom surface to which the foundation layer is exposed, is formed. The trench is filled with the electroconductive pattern layer. The foundation layer includes a mixed region which is formed from a surface of the foundation layer on the electroconductive pattern layer side towards the inside thereof, and contains metal particles which contain a metal configuring the electroconductive pattern layer, and enter the foundation layer.

This is a Continuation of application Ser. No. 16/038,491 filed Jul. 18,2018, which claims the benefit of Japanese Patent Application No. JP2017-146672 filed Jul. 28, 2017. The disclosure of the priorapplications is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to an electroconductive substrate, anelectronic device, and a display device.

BACKGROUND

There is a case where a transparent antenna provided with anelectroconductive substrate having transparency and electroconductivity,is mounted on a surface of a touch panel or a display. Currently, theelectroconductive substrate has been required to have high transparencyand electroconductivity, and high flexibility, according to an increasein the size and diversification of the touch panel and the display. Anelectroconductive substrate of the related art, for example, includes anelectroconductive pattern layer which is formed of a resin containingITO, a metal foil, or an electroconductive nanowire, and forms a finepattern, on a transparent base material.

However, ITO or the electroconductive nanowire is an expensive material.In addition, etching is general as a method of forming a fineelectroconductive pattern layer on a base material, but in the methodusing etching, steps such as an exposing step, a developing step, anetching step, and a peeling step, are necessary, and the number of stepsincreases. For such a reason, there is a limit to produce anelectroconductive substrate at low cost.

In Japanese Unexamined Patent Publication No. 2016-164694, a method isdisclosed in which a trench is formed on a transparent base materialformed of a resin, the entire surface of the transparent base materialis filled with an electroconductive material such as copper according toa vapor deposition method or a sputtering method, the electroconductivematerial except for that in the trench is removed by etching, and thus,an electroconductive layer is formed, as a method of producing theelectroconductive substrate at low cost. On the other hand, inInternational Publication No. 2014/153895, a method is disclosed inwhich a trench is formed on a transparent base material formed of aresin, and the trench is filled with an electroconductive material.

SUMMARY

However, in the electroconductive substrate of the related art,including the electroconductive pattern layer filling the trench, theelectroconductive layer is peeled off, or electroconductivity decreases,at the time of repeatedly bending the electroconductive substrate.

An object of the present invention is to provide an electroconductivesubstrate in which an electroconductive pattern layer filling a trenchis provided, and the peeling of the electroconductive pattern layer anda decrease in electroconductivity due to bending are suppressed, and anelectronic device and a display device, using the electroconductivesubstrate.

Means for Solving the Problem

According to one aspect of the present invention, an electroconductivesubstrate, including: a base material; a foundation layer which isdisposed on a base material and contains a catalyst; a trench formationlayer disposed on the foundation layer; and an electroconductive patternlayer including metal plating, is provided. A trench including a bottomsurface to which the foundation layer is exposed, and a lateral surfacewhich includes a surface of the trench formation layer, is formed. Thetrench is filled with the electroconductive pattern layer. Thefoundation layer includes a mixed region which is formed from a surfaceof the foundation layer on the electroconductive pattern layer sidetowards the inside thereof, and contains metal particles containing ametal configuring the electroconductive pattern layer, and entering thefoundation layer.

It is preferable that a ratio of a thickness of the mixed layer to athickness of the foundation layer is 0.1 to 0.9.

A width of the electroconductive pattern layer may be 0.3 μm to 5.0 μm.A ratio of the thickness of the electroconductive pattern layer to thewidth of the electroconductive pattern layer may be 0.1 to 10.0.

It is preferable that surface roughness Ra of a surface of theelectroconductive pattern layer on a side opposite to the bottom surfaceof the trench is less than or equal to 100 nm.

It is preferable that a gap is formed between at least a part of alateral surface of the electroconductive pattern layer and the lateralsurface of the trench.

The electroconductive pattern layer may include a blackened surfacewhich configures a surface of the electroconductive pattern layer,including a surface on a side opposite to the bottom surface of thetrench. Surface roughness Ra of the blackened surface may be 15 nm to 60nm.

The electroconductive substrate may further include: a protective filmcovering at least a part of a surface of the trench formation layer andthe electroconductive pattern layer on a side opposite to the basematerial. It is preferable that a refractive index of the protectivefilm is greater than 1.0, and is less than a refractive index of thetrench formation layer.

The electroconductive pattern layer may form a mesh-like pattern.

According to another aspect of the present invention, an electronicdevice, including: the electroconductive substrate described above; andan electronic component mounted on the electroconductive substrate, isprovided.

According to still another aspect of the present invention, a displaydevice, including: the electroconductive substrate described above; anda light emitting element mounted on the electroconductive substrate, isprovided.

The electronic device or the display device, may further include: aconnection portion disposed on the electroconductive pattern layer ofthe electroconductive substrate, and the light emitting element may beconnected to the electroconductive substrate through the connectionportion.

The electronic device or the display device, may further include: anadhesion layer disposed on the electroconductive pattern layer of theelectroconductive substrate; an insulating layer which is disposed onthe trench formation layer and the adhesion layer, covers a surface ofthe trench formation layer on a side opposite to the foundation layer,and includes an opening portion to which a part of the adhesion layer isexposed; a UBM layer disposed on a surface of the adhesion layer whichis exposed into the opening portion of the adhesion layer, and aconnection portion disposed on the UBM layer, and the light emittingelement may be connected to the electroconductive substrate through theconnection portion, the UBM layer, and the adhesion layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view illustrating an electroconductivesubstrate according to one embodiment.

FIG. 2 is a partially enlarged view of the electroconductive substrateillustrated in FIG. 1.

FIGS. 3A to 3E are sectional views schematically illustrating a methodof producing the electroconductive substrate illustrated in FIG. 1.

FIG. 4A is a partially enlarged view illustrating the electroconductivesubstrate according to one embodiment, and FIG. 4B is a partiallyenlarged view illustrating an example of an electroconductive substrateof the related art.

FIG. 5 is a schematic sectional view illustrating the electroconductivesubstrate according to one embodiment.

FIGS. 6A and 6B are sectional views schematically illustrating oneembodiment of a method of producing a display device.

FIGS. 7A to 7C are sectional views schematically illustrating anotherembodiment of the method of producing the display device.

FIGS. 8A to 8F are sectional views schematically illustrating amodification example of the method illustrated in FIGS. 7A to 7C.

FIG. 9 is a plan view schematically illustrating a main part of thedisplay device which is obtained according to the method illustrated inFIGS. 6A to 8F.

FIGS. 10A to 10D are process charts illustrating a method of producingof the electroconductive substrate of the related art.

FIG. 11 is a schematic view of a bending resistance testing machine.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withsuitable reference to the drawings. Here, the present invention is notlimited to the following embodiments.

FIG. 1 is a schematic sectional view illustrating an electroconductivesubstrate according to one embodiment. An electroconductive substrate 1Aillustrated in FIG. 1, includes a film-like base material 2, afoundation layer 3 disposed on the base material 2, a trench formationlayer 4 disposed on a surface of the foundation layer 3 on a sideopposite to the base material 2, and an electroconductive pattern layer8. A trench 6 including a bottom surface 6 a to which the foundationlayer 3 is exposed, and lateral surfaces 6 b and 6 c which include asurface of the trench formation layer 4, is formed, and the trench 6 isfilled with the electroconductive pattern layer 8.

It is preferable that the base material 2 is a transparent basematerial, in particular, is a transparent resin film. The transparentresin film, for example, may be a film of polyethylene terephthalate(PET), polycarbonate (PC), polyethylene naphthalate (PEN), a cycloolefinpolymer (COP), or a polyimide (PI). Alternatively, the base material 2may be a glass substrate, an Si wafer, or the like.

The thickness of the base material 2 may be greater than or equal to 10μm, may be greater than or equal to 20 μm, or may be greater than orequal to 35 μm, and may be less than or equal to 500 μm, may be lessthan or equal to 200 μm, or may be less than or equal to 100 μm.

The foundation layer 3 contains a catalyst and a resin. The resin may bea curable resin, and examples thereof include an amino resin, a cyanateresin, an isocyanate resin, a polyimide resin, an epoxy resin, anoxetane resin, polyester, an allyl resin, a phenolic resin, abenzooxazine resin, a xylene resin, a ketone resin, a furan resin, aCOPNA resin, a silicon resin, a dicyclopentadiene resin, abenzocyclobutene resin, an episulfide resin, an ene-thiol resin, apolyazomethine resin, a polyvinyl benzyl ether compound, acenaphthylene,and a ultraviolet ray curable resin having an unsaturated double bond,or a functional group causing a polymerization reaction by anultraviolet ray, such as cyclic ether and vinyl ether, and the like.

It is preferable that the catalyst contained in the foundation layer 3is an electroless plating catalyst. The electroless plating catalyst maybe a metal selected from Pd, Cu, Ni, Co, Au, Ag, Pd, Rh, Pt, In, and Sn,and Pd is preferable. Only one type of the metal may be independentlyused, or a combination of two or more types thereof may be used, as thecatalyst. In general, the catalyst is dispersed in the resin, ascatalyst particles.

The content of the catalyst in the foundation layer 3, may be greaterthan or equal to 3 mass %, may be greater than or equal to 4 mass %, ormay be greater than or equal to 5 mass %, and may be less than or equalto 50 mass %, may be less than or equal to 40 mass %, or may be lessthan or equal to 25 mass %, on the basis of the total amount of thefoundation layer.

The thickness of the foundation layer 3, may be greater than or equal to10 nm, may be greater than or equal to 20 nm, or may be greater than orequal to 30 nm, and may be less than or equal to 500 nm, may be lessthan or equal to 300 nm, or may be less than or equal to 150 nm.

It is preferable that the trench formation layer 4 is a transparentresin layer. In addition, the trench formation layer 4 may be a layercontaining an uncured photocurable or thermosetting resin. Examples ofthe photocurable resin and the thermosetting resin configuring thetrench formation layer 4, include an acrylic resin, an amino resin, acyanate resin, an isocyanate resin, a polyimide resin, an epoxy resin,an oxetane resin, polyester, an allyl resin, a phenolic resin, abenzooxazine resin, a xylene resin, a ketone resin, a furan resin, aCOPNA resin, a silicon resin, a dicyclopentadiene resin, abenzocyclobutene resin, an episulfide resin, an ene-thiol resin, apolyazomethine resin, a polyvinyl benzyl ether compound, acenaphthylene,and an ultraviolet ray curable resin having an unsaturated double bond,or a functional group causing a polymerization reaction by anultraviolet ray, such as cyclic ether and vinyl ether, and the like.

It is preferable that a refractive index (nd25) of the trench formationlayer 4 is less than a refractive index of the foundation layer 3, fromthe viewpoint of increasing the transparency of the electroconductivesubstrate, and for example, may be greater than or equal to 1.0, and maybe less than or equal to 1.7, may be less than or equal to 1.6, or maybe less than or equal to 1.5. The refractive index can be measured by areflecting spectrographic film thickness meter.

The trench 6 includes the bottom surface 6 a to which the foundationlayer 3 is exposed, and the facing lateral surfaces 6 b and 6 c whichinclude the surface of the trench formation layer 4 surrounding thebottom surface 6 a. The trench 6 extends on the foundation layer 3, suchthat a pattern corresponding to the electroconductive pattern layer 8 isformed. As illustrated in FIG. 1, the lateral surfaces 6 b and 6 c maybe inclined with respect to the bottom surface 6 a such that the widthof the trench 6 is narrowed from a surface 4 a of the trench formationlayer 4 on a side opposite to the foundation layer 3 towards the bottomsurface 6 a, or the lateral surfaces 6 b and 6 c may be perpendicular tothe bottom surface 6 a. The lateral surfaces 6 b and 6 c may form astep.

In general, the width and the depth of the trench 6 are respectively setto be substantially coincident with the width and the thickness of theelectroconductive pattern layer 8. Herein, the width of the trenchindicates the maximum width in a direction perpendicular to a directionin which the trench extends. A ratio of the depth of the trench to thewidth of the trench, may be identical to an aspect ratio of theelectroconductive pattern layer described below.

The electroconductive pattern layer 8 may be a layer formed of singlemetal plating, or may be configured of a plurality of metal platingshaving different metals. For example, the electroconductive patternlayer 8 may include a seed layer which is metal plating formed on thefoundation layer 3, and one or more upper metal plating layers which aremetal plating formed on a surface of the seed layer on a side oppositeto the foundation layer 3.

The metal plating as the electroconductive pattern layer 8, for example,contains at least one type of metal selected from copper, nickel,cobalt, palladium, silver, gold, platinum, and tin, and preferablycontains copper. The electroconductive pattern layer 8 may furthercontain a non-metal element such as phosphorus, within a range wheresuitable electroconductivity is maintained.

In a case where the electroconductive pattern layer 8 includes the seedlayer and the upper metal plating layer, a metal configuring the seedlayer and a metal configuring the upper metal plating layer may beidentical to each other, or may be different from each other, and forexample, the seed layer may contain nickel, and the upper metal platinglayer may contain copper. The upper metal plating layer may include acopper plating layer formed on the seed layer, and an uppermost layerformed on the copper plating layer, containing gold or palladium.

The electroconductive pattern layer 8 extends on the foundation layer 3such that a pattern corresponding to the trench 6 is formed. Thethickness of the electroconductive pattern layer 8 may be substantiallycoincident with the thickness of the trench formation layer 4, and aratio of the thickness of the electroconductive pattern layer 8 to thethickness of the trench formation layer 4 may be within a range of 0.8to 1.2.

The width of the electroconductive pattern layer 8, may be greater thanor equal to 1 μm, may be greater than or equal to 10 μm, or may begreater than or equal to 20 pin, and may be less than or equal to 90 μm,may be less than or equal to 70 μm, or may be less than or equal to 30μm. Herein, the width of the electroconductive pattern layer indicatesthe maximum width in a direction perpendicular to an extending directionof the electroconductive pattern layer.

The width of the electroconductive pattern layer 8, may be greater thanor equal to 0.3 μm, may be greater than or equal to 0.5 μm, or may begreater than or equal to 1.0 μm, and may be less than or equal to 5.0μm, may be less than or equal to 4.0 μm, or may be less than or equal to3.0 μm, from the viewpoint of improving the transparency of theelectroconductive substrate.

The thickness of the electroconductive pattern layer 8, may be greaterthan or equal to 0.1 μm, may be greater than or equal to 1.0 μm, or maybe greater than or equal to 2.0 μm, and may be less than or equal to10.0 μm, may be less than or equal to 5.0 μm, or may be less than orequal to 3.0 μm. The width and the thickness of the electroconductivepattern layer 8 can be adjusted by changing the design of a mold 7described below, and by changing the width and the thickness of thetrench 6.

An aspect ratio of the electroconductive pattern layer 8, may be greaterthan or equal to 0.1, may be greater than or equal to 0.5, or may begreater than or equal to 1.0, and may be less than or equal to 10.0, maybe less than or equal to 7.0, or may be less than or equal to 4.0. Bysetting the aspect ratio of the electroconductive pattern layer 8 to bein the range described above, it is possible to further increase theadhesiveness of the electroconductive pattern layer 8 with respect tothe foundation layer 3, and to further increase the electroconductivity.The aspect ratio of the electroconductive pattern layer indicates aratio of the thickness of the electroconductive pattern layer to thewidth of the electroconductive pattern layer (Thickness/Width).

The electroconductive pattern layer 8, for example, may include aplurality of linear portions arranged while extending along a certaindirection, and may be formed into the shape of a mesh.

FIG. 2 is an enlarged view of a region R, in the sectional view of theelectroconductive substrate 1 illustrated in FIG. 1. As illustrated inFIG. 2, the foundation layer 3 includes a mixed region 20 which isformed from a surface of the foundation layer 3 on the electroconductivepattern layer 8 side (or an upper boundary M) to the inside thereof, andcontaining a plurality of metal particles 8R which contain a metalconfiguring the electroconductive pattern layer 8 and entering thefoundation layer 3. The mixed region 20 contains the metal particles 8R,and a resin 31 and catalyst particles 32, which are main components ofthe foundation layer 3. In general, the metal particles 8R include metalplating grown starting from the catalyst particles 32. For this reason,there are many cases where the catalyst particles 32 are incorporatedinto the metal particles 8R. It is preferable that at least a part ofthe plurality of metal particles 8R is continuously connected from theelectroconductive pattern layer 8 to the mixed region 20. It is possibleto confirm that the mixed region 20 is formed, for example, byperforming observation with an electron scanning microscope.

A thickness T of the mixed region 20 is preferably greater than or equalto 1 nm, is more preferably greater than or equal to 5 nm, and is evenmore preferably greater than or equal to 10 nm, and is preferably lessthan or equal to 500 nm, is more preferably less than or equal to 300nm, is even more preferably less than or equal to 200 nm, and isparticularly preferably less than or equal to 100 nm, from the viewpointof further increase the adhesiveness of the electroconductive substrate1.

Here, the thickness T of the mixed region 20 is defined as a distancefrom the upper boundary M on the electroconductive pattern layer 8 sideto a lower boundary N on the base material 2 side. Each of the upperboundary M and the lower boundary N is a sectional surface in adirection perpendicular to a thickness direction of theelectroconductive substrate 1 (hereinafter, referred to as a “horizontalplane”). The upper boundary M is positioned to be closest to theelectroconductive pattern layer side, in a horizontal plane containingthe resin 31 configuring the foundation layer 3. The lower boundary N ispositioned to be closest to the base material 2 side, in a horizontalplane containing the metal particles 8R. The upper boundary M and thelower boundary N can be determined by observing a sectional surfacealong the thickness direction of the electroconductive substrate 1A(hereinafter, referred to as a “perpendicular plane”) with an electronscanning microscope or the like. The thickness T of the mixed region maybe obtained by observing a plurality of perpendicular planes, and theaverage value thereof may be considered as the thickness T of the mixedregion 20 of the electroconductive substrate 1. The mixed region isformed, and thus, the electroconductive pattern layer 8 can beeffectively prevented from being peeled off from the foundation layer 3.

A ratio of the thickness T of the mixed region 20 to the thickness ofthe foundation layer 3 is preferably greater than or equal to 0.1, ismore preferably greater than or equal to 0.2, and is even morepreferably greater than or equal to 0.3, and is preferably less than orequal to 0.9, is more preferably less than or equal to 0.6, and is evenmore preferably less than or equal to 0.5.

Surface roughness Ra of a surface 8 a of the electroconductive patternlayer 8 on a side opposite to the bottom surface 6 a of the trench 6 ispreferably less than or equal to 100 nm, is more preferably less than orequal to 70 nm, and is even more preferably less than or equal to 30 nm.In a case where the surface roughness Ra of the surface 8 a of theelectroconductive pattern layer 8 is less than or equal to 100 nm, it ispossible to decrease a loss in a skin effect. The lower limit value ofthe surface roughness Ra is not particularly limited, and for example,is greater than or equal to 5 nm. A lateral surface of theelectroconductive pattern layer 8 may have surface roughness Ra withinthe numerical range described above.

A gap may be formed between at least a part of the lateral surface ofthe electroconductive pattern layer 8 and the lateral surfaces 6 band/or 6 c of the trench 6. Accordingly, it is possible to moreeffectively suppress a damage on the electroconductive pattern layer 8if the electroconductive substrate 1A is bent. It is preferable that thegap is formed between the lateral surface of the electroconductivepattern layer 8 and both of facing lateral surfaces 6 b and 6 c of thetrench 6. The width of the gap, may be greater than or equal to 1 nm,may be greater than or equal to 5 nm, or may be greater than or equal to10 nm, and may be less than or equal to 150 nm, may be less than orequal to 125 nm, or may be less than or equal to 100 nm. The width ofthe gap indicates the maximum value of a distance between theelectroconductive pattern layer 8 and the trench 6, in a directionperpendicular to an extending direction of the electroconductive patternlayer 8. As described below, it is possible to easily form the gapbetween the electroconductive pattern layer 8 and the lateral surfaces 6b and 6 c of the trench, by growing the metal plating from thefoundation layer 3, or the seed layer on the foundation layer 3.

FIGS. 3A to 3E are sectional views schematically illustrating oneembodiment of the method of producing the electroconductive substrate 1Aillustrated in FIG. 1. In the method according to this embodiment,first, as illustrated in FIG. 3A, the foundation layer 3 containing acatalyst is formed on one main surface 2 a of the film-like basematerial 2. A step of FIG. 3A may be a step of preparing a laminatedbody including the base material 2, and the foundation layer 3 formed onthe base material 2.

Subsequently, as illustrated in FIG. 3B, the trench formation layer 4 isformed on a surface 3 a of the foundation layer 3 on a side opposite tothe base material 2. A step of FIG. 3B may be a step of preparing alaminated body 5A including the base material 2, the foundation layer 3,and the trench formation layer 4 in this order.

Next, as illustrated in FIG. 3C and FIG. 3D, the trench (a grooveportion) 6 is formed according to an imprint method using the mold 7including a convex portion 7 a. In this step, the mold 7 including theconvex portion 7 a having a predetermined shape, is moved in a directionillustrated by an arrow A, and thus, is pushed into the trench formationlayer 4 (FIG. 3C). The mold 7 may be pushed until a tip end of theconvex portion 7 a reaches the foundation layer 3. In this state, in acase where the trench formation layer 4 is a layer containing an uncuredphotocurable or thermosetting resin, the trench formation layer 4 iscured. In a case where the trench formation layer 4 is a layercontaining a photocurable resin, the trench formation layer 4 is curedby being irradiated with light such as an ultraviolet ray. After that,the mold 7 is detached, and thus, the trench 6 having a shape on whichthe shape of the convex portion 7 a of the mold 7 is reflected, isformed (FIG. 3D). A method of forming the trench 6 is not limited to theimprint method, and for example, the trench 6 may be formed by a laser,dry etching, or photolithography.

As illustrated in FIG. 3D, the trench 6 includes the bottom surface 6 ato which the foundation layer 3 is exposed, and the facing lateralsurfaces 6 b and 6 c which include the surface of the trench formationlayer 4 surrounding the bottom surface 6 a. The trench 6 extends on thefoundation layer 3 such that a pattern corresponding to theelectroconductive pattern layer 8 is formed. In order to expose thefoundation layer 3 to the bottom surface 6 a of the trench 6, the trenchformation layer 4 remaining on the foundation layer 3 in the trench 6may be removed by etching such as dry etching, after the mold 7 isdetached.

The mold 7 may be formed of quartz, Ni, ultraviolet ray curable liquidsilicone rubber (PDMS), and the like. The shape of the convex portion 7a of the mold 7 is designed according to the shape of the trench 6 to beformed.

Next, as illustrated in FIG. 3E, the electroconductive pattern layer 8filling the trench 6, is formed. The electroconductive pattern layer 8may be formed by an electroless plating method of growing the metalplating from the foundation layer 3. The laminated body 5A in which thetrench 6 is formed, is dipped in an electroless plating liquidcontaining a metal ion, and thus, metal plating as the electroconductivepattern layer 8 can be formed starting from the catalyst contained inthe foundation layer 3. The electroconductive pattern layer 8 fillingthe trench 6 is formed, and thus, the electroconductive substrate 1A canbe obtained.

The electroless plating liquid contains the ion of the metal configuringthe electroconductive pattern layer. The electroless plating liquid mayfurther contain phosphorus, boron, iron, and the like.

The temperature of the electroless plating liquid at the time of dippingthe laminated body 5A in the electroless plating liquid, for example,may be 40° C. to 90° C. In addition, a dipping time of the electrolessplating liquid is different according to the thickness of theelectroconductive pattern layer 8, and for example, 10 minutes to 30minutes.

The electroconductive pattern layer including the seed layer and theupper metal plating layer, can be formed by a method including formingthe seed layer on the foundation layer, and forming the upper metalplating layer on the seed layer. The laminated body 5A in which thetrench 6 is formed, is dipped in the electroless plating liquid forforming the seed layer, and thus, the metal plating is formed startingfrom the catalyst contained in the foundation layer 3, as the seedlayer. After that, the laminated body including the seed layer is dippedin the electroless plating liquid for forming an electroconductivelayer, and thus, the upper metal plating layer can be formed. Thecatalyst may be adsorbed in the seed layer before the upper metalplating layer is formed, and the upper metal plating layer may be formedstarting from the catalyst adsorbed in the seed layer.

The thickness of the seed layer, may be greater than or equal to 10 nm,may be greater than or equal to 30 nm, or may be greater than or equalto 50 nm, and may be less than or equal to 500 nm, may be less than orequal to 300 nm, or may be less than or equal to 100 nm.

The method according to this embodiment is excellent from the viewpointof enabling the electroconductive pattern layer having a constant widthto be easily formed. FIGS. 4A and 4B are partially enlarged viewsillustrating an example of the electroconductive substrate including theelectroconductive pattern layer forming a mesh-like pattern. In a caseof the electroconductive substrate which is formed by the methodaccording to this embodiment, as exemplified in FIG. 4A, the width ofthe electroconductive pattern layer 8 is not greatly changed even in aregion P in the vicinity of an intersection between twoelectroconductive pattern layers 8, and a constant width is easilymaintained. In contrast, in a case of a method of the related art inwhich the electroconductive pattern layer is formed by etching, asexemplified in FIG. 4B, there is a case where the width of theelectroconductive pattern layer 8′ increases in a region Q in thevicinity of an intersection between two electroconductive pattern layers8′. The fact that a variation in the width of the electroconductivepattern layer is small, and the fact that the width of theelectroconductive pattern layer 8 does not increase in the region in thevicinity of the intersection, are advantageous from the viewpoint ofincreasing a total light transmittance, and the fact that a variation inthe width of the electroconductive pattern layer 8 is small, isadvantageous from the viewpoint of decreasing a variation in the totallight transmittance.

FIG. 5 is a schematic sectional view illustrating another embodiment ofthe electroconductive substrate. The electroconductive pattern layer 8of an electroconductive substrate 1B illustrated in FIG. 5, includes ablackened surface 25 which configures a portion including the surface 8a on a side opposite to the bottom surface 6 a of the trench 6(hereinafter, also referred to as an upper surface 8 a of theelectroconductive pattern layer), and lateral surfaces 8 b and 8 c, inthe surfaces. In the blackened surface 25, “blacken” indicates that asurface is processed such that a normal reflectance with respect tolight incident on the surface of the blackened surface 25, is reduced.

The blackened surface 25 may be black metal plating which is formed byusing a plating liquid for black metal plating, or may be black metalplating which is formed by a Raydent Treatment (Registered Trademark).In general, the blackened surface 25 is disposed as theelectroconductive layer configuring a part of the electroconductivepattern layer 8.

Examples of the black metal plating which is formed by the platingliquid for the black metal plating, include black nickel plating, blackchromium plating, black chromate of zinc plating, black rhodium plating,black ruthenium plating, alloy plating of tin-nickel-copper, alloyplating of tin-nickel, and substituted palladium plating.

The blackened surface 25 may be formed by a method of roughening thesurface of the electroconductive pattern layer 8. In this case, surfaceroughness Ra of the blackened surface 25 is preferably greater than orequal to 15 nm, is more preferably greater than or equal to 20 nm, andis even more preferably greater than or equal to 30 nm, and ispreferably less than or equal to 60 nm, is more preferably less than orequal to 55 nm, and is even more preferably less than or equal to 50 nm.Ra can be measured by a scanning probe microscope (SPM). The rougheningis performed by a method of roughening the surface of theelectroconductive pattern layer 8 according to an acid treatment or thelike, a method of forming the electroconductive pattern layer 8 suchthat the surface of the electroconductive pattern layer 8 is roughened,or the like.

The thickness of the blackened surface 25 (a film of the black metalplating), may be greater than or equal to 10 nm, may be greater than orequal to 30 nm, or may be greater than or equal to 50 nm, and may beless than or equal to 150 nm, may be less than or equal to 125 nm, ormay be less than or equal to 100 nm.

The blackened surface 25 configuring the surface 8 a on the sideopposite to the bottom surface 6 a of the trench 6, for example, can beformed by forming the black metal plating covering the surface 8 a afterthe electroconductive pattern layer 8 is formed. In a case where the gapis formed between the lateral surfaces 8 b and 8 c of theelectroconductive pattern layer 8 and the lateral surface of the trench6, there are many cases where the black metal plating covering not onlythe surface 8 a of the electroconductive pattern layer 8 on the sideopposite to the bottom surface 6 a of the trench 6, but also the lateralsurfaces 8 b and 8 c of the electroconductive pattern layer 8, is formedby being dipped in the plating liquid for the black metal plating.

The blackened surface 25 may be disposed as a layer configuring asurface of the electroconductive pattern layer 8 on the bottom surface 6a side of the trench 6. A blackened surface configuring the surface ofthe electroconductive pattern layer 8 on the bottom surface 6 a side ofthe trench 6, for example, may be formed on the foundation layer 3 byusing the black metal plating (for example, black nickel plating) as theseed layer, after the trench 6 is formed.

The electroconductive substrate may further include a protective filmcovering at least a part of the surface of the trench formation layer 4and the electroconductive pattern layer 8 on a side opposite to the basematerial 2. The protective film, for example, may contain a resin and afiller. Examples of the resin of the protective film, include an aminoresin, an isocyanate resin, a silicon resin, an acrylic resin, apolycarbonate resin, a fluorine resin, and an ultraviolet ray curableresin having an unsaturated double bond, or a functional group causing apolymerization reaction by an ultraviolet ray, such as cyclic ether andvinyl ether, and the like. Examples of the filler of the protectivefilm, include silicon oxide, zirconium oxide, titanium oxide, aluminumoxide, magnesium fluoride zinc oxide, antimony oxide, phosphorus dopedtin oxide, antimony doped tin oxide, tin doped indium oxide, Agnano-colloid, and the like. For example, a resin composition for formingthe protective film is applied onto the surface of the trench formationlayer 4 and the electroconductive pattern layer 8 on the side oppositeto the base material 2, and the coated film is dried and/or cured, asnecessary, and thus, the protective film can be formed. In a case wherethe gap is formed between the electroconductive pattern layer 8 and thelateral surfaces 6 b and 6 c of the trench 6, the protective film mayfill the gap.

The thickness of the protective film, may be greater than or equal to 10nm, may be greater than or equal to 50 nm, or may be greater than orequal to 100 nm, and may be less than or equal to 5000 nm, may be lessthan or equal to 3000 nm, or may be less than or equal to 1000 nm.

A refractive index of the protective film, may be greater than or equalto 1.0, or may be greater than or equal to 1.3, and may be less than orequal to 1.6, or may be less than or equal to 1.5, from the viewpoint ofthe transparency of the electroconductive substrate. It is preferablethat the refractive index of the protective film is less than therefractive index of the trench formation layer 4. The refractive indexof the protective film, for example, can be adjusted by increasing anddecreasing the content of the filler.

[Display Device]

A light emitting element is mounted on the electroconductive substratedescribed above, and thus, it is possible to producing a display deviceincluding the electroconductive substrate and the light emittingelement. In the electroconductive substrate described above, theelectroconductive pattern layer is prevented from being peeled off fromthe foundation layer, and thus, the display device including such anelectroconductive substrate is produced to be thin like cloth or paper,and can be used as a flexible display device (display) which is capableof being folded or rolled. Such a flexible display device can be reducedin the size and the weight, and the storability and the designabilitythereof can be improved.

FIGS. 6A and 6B are sectional views schematically illustrating oneembodiment of a method of producing the display device. In this method,first, as illustrated in FIG. 6A, a light emitting element 40 and theelectroconductive substrate 1A are prepared. The light emitting element40 includes a light emitting unit 41, a positive electrode 42 disposedon one main surface 41 a of the light emitting unit 41, and a negativeelectrode 43 disposed on the main surface 41 a with a space from thepositive electrode 42. Hereinafter, the positive electrode 42 and thenegative electrode 43 may be collectively referred to as electrodes 42and 43. The light emitting element 40 may be an element which is capableof emitting red light, green light, or blue light. The light emittingelement 40, for example, may be a light emitting diode (LED). In thisembodiment, the electroconductive pattern layer 8 of theelectroconductive substrate 1A, includes a plurality of linear portions81 and 82 extending along a certain direction.

The shape of the light emitting element 40 (the shape of the lightemitting unit 41) is not particularly limited, and for example, may bean approximately quadrangular shape (a rectangular shape, a squareshape, and the like). The dimension of the light emitting element 40 maybe suitably set, and in a case where the light emitting element 40 has aquadrangular shape, it is preferable that the width of the lightemitting element 40, is less than or equal to 100 μm, is less than orequal to 80 μm, is less than or equal to 60 μm, is less than or equal to30 μm, or is less than or equal to 20 μm, from the viewpoint of furtherimproving the resolution of the display device. In this case, it ispreferable that the length of the light emitting element 40, is lessthan or equal to 50 μm, is less than or equal to 40 μm, is less than orequal to 30 μm, is less than or equal to 20 μm, or is less than or equalto 10 μm. The width of the light emitting element 40, may be greaterthan or equal to 5 μm, may be greater than or equal to 10 μm, or may begreater than or equal to 20 μm. In this case, the length of the lightemitting element 40, may be greater than or equal to 5 μm, or may begreater than or equal to 10 μm. When the light emitting element 40 ismounted on the electroconductive substrate 1A in a step described below,the width of the light emitting element 40 is set as a directioncorresponding to the width of the electroconductive pattern layer 8. Thelength of the light emitting element 40 is set as a direction along theextending direction of the electroconductive pattern layer 8.

Next, as illustrated in FIG. 6B, the light emitting element 40 ismounted on the electroconductive substrate 1A. Such a step includesconnecting the electrodes 42 and 43 of the light emitting element 40 tothe electroconductive pattern layer 8 of the electroconductive substrate1A. At this time, the positive electrode 42 and the negative electrode43 of the light emitting element 40 are respectively connected to twoadjacent linear portions 81 and 82 of the electroconductive patternlayer 8, and thus, the light emitting element 40 is electricallyconnected to the electroconductive pattern layer 8. Accordingly, it ispossible to obtain a display device 50A in which the light emittingelement 40 is mounted on the electroconductive substrate 1A.

FIGS. 7A to 7C are sectional views schematically illustrating anotherembodiment of the method of producing the display device. Such a methodis different from the method of the embodiment described above, in thatthe step of mounting the light emitting element 40 on theelectroconductive substrate 1A, includes forming a connection portion onthe electroconductive pattern layer 8 of the electroconductive substrate1A, and connecting the light emitting element 40 to theelectroconductive pattern layer 8 through the connection portion.

In this method, first, as illustrated in FIG. 7A and FIG. 7B, aconnection portion 44 is formed on the electroconductive pattern layer 8of the electroconductive substrate 1A. The connection portion 44 may beformed to be in contact with at least a part on the upper surface 8 a ofthe electroconductive pattern layer 8.

The connection portion 44 may be formed on the upper surface 8 a of theelectroconductive pattern layer 8 by using a fine ball formed of asolder alloy, or may be formed by printing a paste formed of a solderalloy. The connection portion 44 may be formed according to anelectroless plating method of growing the metal plating from theelectroconductive pattern layer 8. In a case where the connectionportion 44 is formed according to the electroless plating method, theconnection portion 44 may contain tin, silver, copper, bismuth, indium,and the like, or may contain an alloy of any two or more materials, as aconfiguration material. In this embodiment, it is preferable that theconnection portion 44 is formed by a fine ball or a paste, formed of asolder alloy.

The dimension of the connection portion 44 may be suitably set insofaras being a size in which the electrodes 42 and 43 of the light emittingelement 40 can be in contact with the connection portion 44. Forexample, as illustrated in FIG. 7B, the connection portion 44 may beformed such that the width thereof is identical to the width of theelectroconductive pattern layer 8. The connection portion 44 may beformed such that the width thereof is smaller than the width of theelectroconductive pattern layer 8, and a part of the upper surface 8 aof the electroconductive pattern layer 8 may be exposed.

Next, as illustrated in FIG. 7C, the electrodes 42 and 43 of the lightemitting element 40 are in contact with a surface 44 a of the connectionportion 44 on a side opposite to a surface in contact with theelectroconductive pattern layer 8, and thus, the light emitting element40 is connected to the electroconductive substrate 1A through theconnection portion 44. At this time, the positive electrode 42 and thenegative electrode 43 of the light emitting element 40 are brought intocontact with two adjacent connection portions 44, and thus, the lightemitting element 40 is electrically connected to the electroconductivesubstrate 1A. Accordingly, it is possible to obtain a display device 50Bin which the light emitting element 40 is mounted on theelectroconductive substrate 1A.

FIGS. 8A to 8F are sectional views schematically illustrating onemodification example of the method of producing the display device,including connecting the light emitting element 40 to theelectroconductive substrate 1A through the connection portion 44.According to this modification example, it is possible to more suitablyand easily mount the light emitting element 40 on the electroconductivesubstrate 1A, and thus, this modification example is particularlypreferably used in a case where a smaller light emitting element 40 ismounted on the electroconductive substrate 1A.

In this method, first, as illustrated in FIG. 8A and FIG. 8B, anadhesion layer 45 is formed on the electroconductive pattern layer 8 ofthe electroconductive substrate 1A. The adhesion layer 45 may be formedin at least a part of the upper surface 8 a of the electroconductivepattern layer 8. The adhesion layer 45 is formed, and thus, when aninsulating layer described below is formed on the trench formation layer4 and the electroconductive pattern layer 8, it is possible to preventthe insulating layer from being peeled off.

It is preferable that the adhesion layer 45 is formed according to anelectroless plating method of growing the metal plating from theelectroconductive pattern layer 8. It is preferable that the adhesionlayer 45 contains at least one type selected from nickel and a nickelalloy, as a configuration material, from the viewpoint of improving theadhesiveness with respect to a UBM layer described below, and theconnection portion 44 and the light emitting element 40 disposed on theUBM layer. It is more preferable that the adhesion layer 45 contains atleast one type selected from the group consisting of zinc andphosphorus, in addition to at least one type selected from the groupconsisting of nickel and a nickel alloy.

It is preferable that a surface 45 a of the adhesion layer 45 on a sideopposite to a surface in contact with the electroconductive patternlayer 8 (hereinafter, also referred to as an upper surface 45 a of theadhesion layer 45) is roughened. The upper surface 45 a of the adhesionlayer 45 is roughened, and thus, the insulating layer more easilyadheres to the upper surface 45 a of the adhesion layer 45 according toan anchor effect.

A method of roughening the upper surface 45 a of the adhesion layer 45,is performed by a method of roughening the upper surface 45 a of theadhesion layer 45 after plating according to an acid treatment and thelike, a method of forming the adhesion layer 45 after the plating liquidis adjusted such that a surface of the adhesion layer 45 is roughened,or the like.

Surface roughness Ra of the adhesion layer 45 is preferably greater thanor equal to 0.1 μm, is more preferably greater than or equal to 0.3 μm,and is even more preferably greater than or equal to 0.5 μm, from theviewpoint of further improving the adhesiveness with respect to theinsulating layer described below. Ra is preferably less than or equal to1 μm, is more preferably less than or equal to 0.8 μm, and is even morepreferably less than or equal to 0.7 μm, from the viewpoint of ensuringthe strength of the display device. Ra can be measured by the samemeasurement method as the method described in the blackened surface.

The thickness of the adhesion layer 45 is preferably greater than orequal to 0.1 μm, is more preferably greater than or equal to 0.5 μm, andis even more preferably greater than or equal to 1.0 μm, from theviewpoint of obtaining suitable surface roughness Ra. The thickness ofthe adhesion layer 45, may be less than or equal to 2.0 μm, may be lessthan or equal to 1.8 μm, or may be less than or equal to 1.5 μm.

Subsequently, as illustrated in FIG. 8C, an insulating layer 46, whichcovers the surface 4 a of the trench formation layer 4 on the sideopposite to the foundation layer 3, and includes an opening portion towhich the upper surface 45 a of the adhesion layer 45 is exposed, isformed. It is preferable that the insulating layer 46 is formed to coverthe surface 4 a of the trench formation layer 4, and a part of theadhesion layer 45 (for example, an end portion of the upper surface 45 aof the adhesion layer 45).

The insulating layer 46 is formed of a material having insulatingproperties. The material having the insulating properties may be aninorganic material or a resin. Examples of the inorganic materialinclude a compound containing silicon, such as SiO₂ and SiN. Examples ofthe resin include an epoxy resin, polyimide, and the like.

As illustrated in FIG. 8D, an UBM layer (a under-barrier metal layer) 47is formed on the upper surface 45 a of the adhesion layer 45, which isexposed into the opening portion of the insulating layer 46. It ispreferable that the UBM layer 47 is formed according to an electrolessplating method of growing the metal plating from the adhesion layer 45.The UBM layer 47 may contain at least type of metal selected from thegroup consisting of nickel, cobalt, iron, and copper. The UBM layer 47may further contain a non-metal element such as phosphorus. It ispreferable that the UBM layer 47 contains nickel, or contains nickel andphosphorus.

As illustrated in FIG. 8E, the connection portion 44 is formed on asurface 47 a of the UBM layer 47 on a side opposite to theelectroconductive substrate 1A. A configuration material and a formingmethod of the connection portion 44 may be identical to theconfiguration material and the forming method of the embodimentdescribed above, and in this modification example, it is preferable thatthe connection portion 44 is formed according to an electroless platingmethod of growing the metal plating from the UBM layer 47, from theviewpoint of mounting a smaller light emitting element 40. It ispreferable that the connection portion 44 contains tin or an alloythereof, as a configuration material. A part of the connection portion44 to be formed on the UBM layer 47, may be in contact with a surface ofthe insulating layer 46.

As illustrated in FIG. 8F, the light emitting element 40 is connected tothe formed connection portion 44. Accordingly, it is possible to obtaina display device 50C in which the light emitting element 40 is connectedto the electroconductive pattern layer 8 of the electroconductivesubstrate 1A through the connection portion 44, the UBM layer 47, andthe adhesion layer 45. That is, the light emitting element 40 is mountedon the electroconductive substrate 1A, according to the step forming theadhesion layer 45, the insulating layer 46, the UBM layer 47, and theconnection portion 44, and connecting the light emitting element 40 tothe connection portion 44.

FIG. 9 is a plan view schematically illustrating a main part of adisplay device 50 (50A to 50C) which is obtained according to the methodillustrated in FIGS. 6A to 8F. In the display device 5 illustrated inFIG. 9, a plurality of light emitting elements 40 (40 a, 40 b, and 40 c)are arranged along an extending direction L of two adjacent linearportions while straddling two adjacent linear portions 81 and 82 of theelectroconductive pattern layer 8 of the electroconductive substrate 1A.The light emitting element 40 may be configured of a light emittingelement 40 a including a red light emitting unit, a light emittingelement 40 b including a green light emitting unit, and a light emittingelement 40 c including a blue light emitting unit, and such lightemitting elements 40 a, 40 b, and 40 c may be arranged in an arbitraryorder. For example, a distance D₁ in a width direction of theelectroconductive pattern layer 8 may be less than or equal to 400 μm,and a distance D₂ in the extending direction L of the electroconductivepattern layer 8 may be less than or equal to 200 μm, as a distancebetween the adjacent light emitting elements 40 (40 a, 40 b, and 40 c).

In the method of producing the display device 50 described above, a stepof disposing a sealing portion covering an exposed portion of the lightemitting element 40, may be further provided. The sealing portion, forexample, may be formed of a resin such as a silicone resin, an epoxyresin, and an olefin resin.

It is also possible to mount the light emitting element on theelectroconductive substrate 1B according to another embodiment,according to the same method as that of the first embodiment, and toproduce the display device. In this case, the light emitting element 40may be mounted by being connected onto the blackened surface 25 of theelectroconductive substrate 1B directly or through the connectionportion 44.

[Electronic Device]

In another embodiment, an electronic component other than the lightemitting element can be mounted on the electroconductive substrate whichis produced by the method described above. Examples of the electroniccomponent other than the light emitting element, include a passivecomponent such as a capacitor, an inductor, and a thermistor, asemiconductor element, a connector, and the like. Accordingly, it ispossible to produce an electronic device including an electroniccomponent on the electroconductive substrate which is produced by themethod described above, in addition to the display device.

EXAMPLES

Hereinafter, the present invention will be specifically described byexamples, but the present invention is not limited to the examples.

Example 1

A catalyst-containing resin for forming a foundation layer forming,containing 20 mass % of Pd particles, and an isocyanate resin, wasprepared. The catalyst-containing resin was applied onto a PET film (athickness of 100 μm), which is a transparent base material, by using abar coater. The coated film was heated at 80° C., and was cured, andthus, the foundation layer (a thickness of 100 nm) was formed. Afterthat, an ultraviolet ray curable transparent acryl-based oligomer wasapplied onto the foundation layer, by using a bar coater, and thus, atrench formation layer (a thickness of 2 μm) was formed.

An Ni mold in which a mesh-like pattern was formed and a convex portionhaving a width of 1 μm was provided, was prepared. The mold was pressedagainst the trench formation layer, and a tip end of the convex portionof the mold reached the foundation layer. In such a state, the trenchformation layer was cured by being irradiated with an ultraviolet ray.Accordingly, a trench including a bottom surface to which the foundationlayer was exposed, was formed. The width of the trench was 1 μm, thedepth of the trench was 2 μm, and a distance between adjacent trencheswas 100 μm.

A laminated body including the trench formation layer in which thetrench was formed, was dipped in an alkaline degreasing liquidcontaining a surfactant, for 5 minutes. After that, the laminated bodytaken out from the degreasing liquid, was washed with pure water. Thelaminated body after being washed, was dipped in an electroless platingliquid containing nickel sulfate and sodium hypophosphite, for 3minutes, and metal plating as a seed layer (a thickness of 100 nm)formed of Ni and P, was grown from the foundation layer which wasexposed to the bottom surface of the trench. The laminated body takenout from the electroless plating liquid, was washed with pure water.Subsequently, the laminated body in which the seed layer was formed, wasdipped in an aqueous solution containing Pd, for 5 minutes, and then,was washed with pure water, and the Pd particles as a catalyst wereadsorbed in the seed layer. After that, the laminated body was dipped inan electroless plating liquid containing copper sulfate and formalin,for 5 minutes, and thus, Cu plating (an upper metal plating layer)filling the trench, was grown on the seed layer. The laminated bodytaken out from the electroless plating liquid, was washed with purewater, and was dried at 80° C. for 3 minutes, and a mesh-like patternwas formed, and thus, an electroconductive substrate including anelectroconductive pattern layer formed of the seed layer and the Cuplating, was obtained. In the electroconductive substrate, a width W ofthe electroconductive pattern layer was 1 μm, the thickness of theelectroconductive pattern layer was 2 μm, and an aspect ratio(Thickness/Width) of the electroconductive pattern layer was 2. Adistance S between adjacent electroconductive pattern layers was 200 μm.In the obtained electroconductive substrate, a sectional surface of theelectroconductive pattern layer was cut out by using a cross-sectionpolisher, and it was confirmed that a gap was formed between a lateralsurface of the trench and a lateral surface of the electroconductivepattern layer, according to observation using an electron scanningmicroscope.

Examples 2 to 5

An electroconductive substrate was prepared by the same method as thatin Example 1, except that the width W of the electroconductive patternlayer (the width of the trench) and the thickness of theelectroconductive pattern layer (the depth of the trench) was changed tothe values shown in Table 1.

Examples 6 to 9

An electroconductive substrate was prepared by the same method as thatin Example 1, in that the thickness of the electroconductive patternlayer (the depth of the trench) was changed to the values shown in Table1.

Comparative Example 1

An electroconductive substrate not including the foundation layer, wasprepared according to a production method of the related art illustratedin FIGS. 10A to 10D. First, an ultraviolet ray curable transparentacryl-based oligomer was applied onto the same PET film (the basematerial 2) as that of the examples, and the trench formation layer 4 (athickness 2 of μm) was formed. A mold in which a mesh-like pattern wasformed and a convex portion having a width of 1 μm was provided, waspressed against the trench formation layer 4, and a tip end of theconvex portion reached the base material 2. In such a state, the trenchformation layer 4 was cured by being irradiated with an ultraviolet ray,and thus, a laminated body 5C was obtained in which the trench 6including the bottom surface to which the base material 2 was exposed,was formed (FIG. 10A). Next, a seed layer 11 formed of Cu, covering theentire surface of the trench formation layer 4 and the entire bottomsurface 6 a, was formed by a sputtering method (FIG. 10B). After that,the laminated body 5C was dipped in an electroless plating liquidcontaining copper sulfate and formalin, and thus, Cu plating was grownfrom the seed layer 11, and a Cu plating layer 8A which filled thetrench 6 and covered the entire trench formation layer 4, was formed(FIG. 10C). After that, a portion of the Cu plating layer 8A, other thana portion filling the inside of the trench 6, was removed by etching(FIG. 10D), and thus, an electroconductive substrate 1C according toComparative Example 1, including the electroconductive pattern layer 8,was prepared. In the obtained electroconductive substrate, the sectionalsurface of the electroconductive pattern layer was cut out by using across-section polisher, and it was confirmed that the electroconductivepattern layer 8 adhered to the lateral surfaces 6 b and 6 c of thetrench 6, and a gap was not formed therebetween, according toobservation using an electron scanning microscope.

In each of the electroconductive substrates, surface roughness Ra of asurface of the electroconductive pattern layer on a side opposite to thebottom surface of the trench, was measured in a visual field of 1 μm, byusing a scanning probe microscope. In addition, the sectional surface(the perpendicular plane) of each of the electroconductive substrateswas observed, and it was confirmed that a mixed region was formed inwhich particles containing nickel which is a metal configuring the seedlayer of the electroconductive pattern layer, entered the foundationlayer. In the mixed region, a plurality of metal particles werecontinuously connected from the electroconductive pattern layer. Thethickness of the mixed region was measured on the basis of theobservation of the perpendicular plane. In the electroconductivesubstrate of Comparative Example 1, the mixed region was not formed.

<Bending Test>

A sample of each electroconductive substrate having a length of 150 mmand a width of 50 mm, was prepared. The sample was subjected to abending test according to JISC5016, using a bending resistance testingmachine illustrated in FIG. 11. That is, the electroconductive substrate1 was set to conform to a circular circumferential surface (CurvatureRadius d: 5 mm) of a bent portion 14 while fixing an end portion 12 ofthe electroconductive substrate 1 to a fixation portion 13, and thus,the electroconductive substrate 1 was disposed to be bent. After that,an end portion 15 on a side opposite to the end portion 12 was movedback and forth along a direction illustrated by an arrow B. A movementdistance that the end portion 15 was moved back and forth, was set to 30mm, and a back and forth cycle was set to 150 times/minute, and thus,the end portion 15 was repeatedly moved back and forth for 1 minute.

<Evaluation of Electroconductivity (Measurement of Surface Resistance)>

Surface resistance of each of the electroconductive substrates beforeand after the bending test was measured by using a non-contact typeresistance measuring instrument EC-80P (manufactured by NAPSONCORPORATION). The measurement was performed in a region of ϕ20 mm of asurface of the electroconductive substrate. Electroconductivity wasevaluated in the following four ranks, on the basis of the measurementresult. A rank A indicates that the electroconductivity is mostexcellent.

Rank A: The surface resistance is less than 5 Ω/square

Rank B: The surface resistance is greater than or equal to 5 Ω/squareand less than 10 Ω/square

Rank C: The surface resistance is greater than or equal to 10 Ω/squareand less than 15 Ω/square

Rank D: The surface resistance is greater than or equal to 15 Ω/square

<Evaluation of Adhesiveness>

A sectional surface of the electroconductive substrate after the bendingtest, was observed with an electron scanning microscope, and thepresence or absence of the peeling of the electroconductive patternlayer from the foundation layer or the base material was confirmed.

<Evaluation of Transparency>

A total light transmittance of the electroconductive substrate wasmeasured according to JISK7136, using a haze meter NDH5000 (manufacturedby NIPPON DENSHOKU INDUSTRIES CO., LTD.). The transparency of thetransparent electroconductive substrate was evaluated in the followingthree ranks, with respect to the measurement result. A rank A indicatesthat the transparency is most excellent.

Rank A: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=greater than or equal to 98%

Rank B: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=greater than or equal to 96%and less than 98%

Rank C: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=less than 96%

TABLE 1 Electroconductive pattern layer (trench) Evaluation resultThickness Presence of After bending test W/S Thickness Aspect of mixedRa absence Electro- Peeling Electro- (μm) (μm) ratio region (nm) (nm) ofgap Transparency conductivity (adhesiveness) conductivity Example 11/200 2 2 38 8 Present B B Absent B Example 2 0.3/200  0.6 2 38 8Present A C Absent C Example 3 0.5/200  1 2 38 8 Present A B Absent BExample 4 3/200 6 2 38 8 Present B A Absent A Example 5 3.5/200  7 2 388 Present C A Absent A Example 6 1/200 4.5 4.5 38 8 Present C A Absent AExample 7 1/200 4 4 38 8 Present B A Absent A Example 8 1/200 1 1 38 8Present B B Absent B Example 9 1/200 0.5 0.5 38 8 Present A B Absent CComparative 1/200 2 2 Absent 8 Absent B B Present D Example 1

As shown in Table 1, in the electroconductive substrates of Examples 1to 9, it was found that the electroconductive pattern layer after thebending test was prevented from being peeled off, and excellentelectroconductivity was maintained.

Examples 10 to 12

A plurality of electroconductive substrates were prepared by the samemethod as that in Example 1. Such electroconductive substrates weredipped in an aqueous solution containing Pd, for 5 minutes, and then,were washed with pure water, and thus, the Pd particles as the catalystwere adsorbed in the surface of the electroconductive pattern layer.After that, the electroconductive substrate was dipped in an electrolessplating liquid for black Ni plating, for 3 minutes, and thus, a black Niplating film was formed as the uppermost layer of the electroconductivepattern layer on a side opposite to the bottom surface of the trench andon the lateral surface side of the trench. Each of the electroconductivesubstrates taken out from the electroless plating liquid, was washedwith pure water. Further, the black Ni plating film was subjected to anacid treatment, surface roughness Ra of the black Ni plating film wasadjusted to be 15 nm (Example 10), 58 nm (Example 11), or 65 nm (Example12), by adjusting the time of the acid treatment. The surface roughnessRa and the thickness of the mixed region were measured by the samemethod as that in Examples 1 to 9.

<Evaluation of Electroconductivity and Measurement of Transmittance>

In the electroconductive substrates of Examples 10 to 12 and Example 1,the transparency and the electroconductivity were evaluated by the samemethod as the method described above. As shown in Table 2, it was foundthat when Ra was 15 nm to 60 nm, the transparency and theelectroconductivity were particularly excellent.

TABLE 2 Electroconductive pattern layer (trench) W/S Thickness Thicknessof Ra Evaluation result (μm) (μm) mixed region (nm) (nm) TransparencyElectroconductivity Example 1 1/200 2 38 8 B B Example 10 1/200 2 38 15A B Example 11 1/200 2 38 58 A B Example 12 1/200 2 38 65 A C

Examples 13 to 15

A plurality of electroconductive substrates were prepared by the samemethod as that in Example 1. A curable resin composition for forming aprotective film was applied onto the surface of the trench formationlayer and the electroconductive pattern layer of such electroconductivesubstrates, with a doctor blade. The coated film was dried, and then,was cured by being irradiated with an ultraviolet ray, and thus, theprotective film (a thickness 100 nm) covering the trench formation layerand the electroconductive pattern, was formed. The curable resincomposition for forming the protective film, used here, contains afiller (silicon oxide) and a fluorine resin. A refractive index of theprotective film was adjusted to be the values shown in Table 3 bychanging the content of the filler. The thickness of the mixed regionwas measured by the same method as that in Examples 1 to 9.

<Evaluation of Transparency>

In the electroconductive substrates of Examples 13 to 15 and Example 1,the transparency of the electroconductive substrate was measured by thesame method as the method described above. The results are shown inTable 3. As shown in Table 3, it was found that in a case where therefractive index of the protective film was greater than a refractiveindex of the air of 1.0, and was less than the refractive index of thetrench formation layer, the transparency was particularly excellent.

TABLE 3 Electroconductive pattern layer (trench formation layer)Protective film W/S Thickness Refractive index of Content of RefractiveEvaluation result (μm) (μm) trench formation layer filler (mass %) indexTransparency Example 1 1/200 2 1.51 — (1.0)  B Example 13 1/200 2 1.5182 1.33 A Example 14 1/200 2 1.51 25 1.50 B Example 15 1/200 2 1.51 61.55 C

According to the present invention, it is possible to produce theelectroconductive substrate in which the electroconductive pattern layerfilling the trench is provided, and the peeling of the electroconductivepattern layer and a decrease in the electroconductivity due to bendingare suppressed, and the electronic device using the electroconductivesubstrate.

Further, the present invention is also capable of providing the displaydevice in which in the electroconductive substrate, the peeling of theelectroconductive pattern layer is suppressed. Recently, a displaydevice (for example, an LED display) including a light emitting elementsuch as a light emitting diode (LED) has developed. In a liquid crystaldisplay (LCD), backlight is controlled by transmissive liquid crystals,but in the LED display, a pixel is configured by using a light emittingdiode which is a natural light emitting element. Accordingly, the LEDdisplay has characteristics such as a high brightness, long lifetime,and a high viewing angle.

In the display device including the light emitting element, it ispreferable to decrease the size of the light emitting element itself, inorder to improve the resolution. However, in a case where the size ofthe light emitting element decreases, it is necessary to form a fineelectroconductive pattern layer, and thus, there is a tendency that theelectroconductive pattern layer is easily peeled off, and theelectroconductivity is difficult to be ensured. According to the presentinvention, it is possible to easily producing the display device inwhich even in a case where the size of the light emitting elementdecreases, the electroconductive pattern layer of the electroconductivesubstrate is hardly peeled off, and adhesiveness between the lightemitting element and the electroconductive substrate is excellent.

-   -   1A, 1B: electroconductive substrate, 2: base material, 3:        foundation layer, 4: trench formation layer, 6: trench, 6 a:        bottom surface of trench, 6 b, 6 c: lateral surface of trench,        8: electroconductive pattern layer, 8 a: surface of        electroconductive pattern layer on side opposite to bottom        surface of trench, 8 b, 8 c: lateral surface of        electroconductive pattern layer, 8R: metal particles, 20: mixed        region, 25: blackened surface, 31: resin, 32: catalyst        particles, T: thickness of mixed region, 40: light emitting        element, 44: connection portion, 45: adhesion layer, 46:        insulating layer, 47: UBM layer, 50: display device.

What is claimed is:
 1. An electroconductive substrate comprising: a basematerial; a foundation layer which is disposed on the base material andcontains a catalyst and a resin; a trench formation layer disposed onthe foundation layer; and an electroconductive pattern layer includingmetal plating, wherein: the trench formation layer includes a trenchhaving (1) a bottom surface that exposes the foundation layer and (2) alateral surface which includes a surface of the trench formation layer;the trench is at least partially filled with the electroconductivepattern layer; the catalyst is dispersed in the resin, as catalystparticles; the foundation layer includes a mixed region (1) whichextends from the electroconductive pattern layer towards the basematerial and (2) in which metal particles of a metal of theelectroconductive pattern layer are in the foundation layer such thatthe mixed region includes a mixture of the metal particles, the catalystand the resin; and the mixed region has a thickness that is less than athickness of the foundation layer such that a portion of the foundationlayer containing the catalyst and the resin but not the metal particlesis between the mixed region and the base material.
 2. Theelectroconductive substrate according to claim 1, wherein a ratio of thethickness of the mixed region to the thickness of the foundation layeris 0.1 to 0.9.
 3. The electroconductive substrate according to claim 1,wherein: a width of the electroconductive pattern layer is 0.3 μm to 5.0μm; and a ratio of the thickness of the electroconductive pattern layerto the width of the electroconductive pattern layer is 0.1 to 10.0. 4.The electroconductive substrate according to claim 1, wherein a gap isformed between at least a part of a lateral surface of theelectroconductive pattern layer and the lateral surface of the trench.5. The electroconductive substrate according to claim 1, wherein thesurface of the electroconductive pattern layer opposite to the bottomsurface of the trench is a blackened surface and the surface roughnessRa is 15 nm to 60 nm.
 6. The electroconductive substrate according toclaim 1, further comprising: a protective film covering at least a partof a surface of the trench formation layer and the electroconductivepattern layer on a side opposite to the base material, wherein arefractive index of the protective film is greater than 1.0, and is lessthan a refractive index of the trench formation layer.
 7. Theelectroconductive substrate according to claim 1, wherein theelectroconductive pattern layer forms a mesh-like pattern.
 8. Anelectronic device, comprising: the electroconductive substrate accordingto claim 1; and an electronic component mounted on the electroconductivesubstrate.
 9. The electronic device according to claim 8, furthercomprising: a connection portion disposed on the electroconductivepattern layer, wherein the electronic component is connected to theelectroconductive substrate through the connection portion.
 10. Theelectronic device according to claim 8, further comprising: an adhesionlayer disposed on the electroconductive pattern layer; an insulatinglayer which (1) is disposed on the trench formation layer and theadhesion layer, (2) covers a surface of the trench formation layer on aside opposite to the foundation layer, and (3) includes an openingportion to which a part of the adhesion layer is exposed; a UBM layerdisposed on a surface of the adhesion layer which is exposed into theopening portion of the insulating layer; and a connection portiondisposed on the UBM layer, wherein the electronic component is connectedto the electroconductive substrate through the connection portion, theUBM layer, and the adhesion layer.
 11. A display device, comprising: theelectroconductive substrate according to claim 1; and a light emittingelement mounted on the electroconductive substrate.
 12. The displaydevice according to claim 11, further comprising: a connection portiondisposed on the electroconductive pattern layer, wherein the lightemitting element is connected to the electroconductive substrate throughthe connection portion.
 13. The display device according to claim 11,further comprising: an adhesion layer disposed on the electroconductivepattern layer; an insulating layer which (1) is disposed on the trenchformation layer and the adhesion layer, (2) covers a surface of thetrench formation layer on a side opposite to the foundation layer, and(3) includes an opening portion to which a part of the adhesion layer isexposed; a UBM layer disposed on a surface of the adhesion layer whichis exposed into the opening portion of the insulating layer; and aconnection portion disposed on the UBM layer, wherein the light emittingelement is connected to the electroconductive substrate through theconnection portion, the UBM layer, and the adhesion layer.